Also known as: expressly conditional on assent · conditional acceptance · counteroffer
Written by attorneys · grounded in primary & secondary sources — see below
A proviso attached to a response to an offer that requires the offeror's agreement to any additional or different terms before the response can serve as an acceptance. The proviso prevents the response from operating as an acceptance even if the response is otherwise definite and seasonable.
Metro Ed sent First Academy a purchase order accepting a quoted price for textbooks but adding a buyback term for unsold copies. The order stated that acceptance was limited to its own terms. First Academy shipped the books without agreeing to the buyback term. The conditional language prevented the purchase order from operating as an acceptance, so the buyback term never entered the contract formed by the parties' conduct.
Step-Saver ordered software from Wyse Technology. Wyse sent an acknowledgment that added a warranty disclaimer and stated the acknowledgment was conditional on assent to the new term. Step-Saver installed the software without expressly agreeing to the disclaimer. The conditional language kept the acknowledgment from operating as an acceptance, leaving the disclaimer outside the contract formed by the parties' conduct.
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Language that clearly states the response will not operate as an acceptance unless the offeror agrees to the added terms prevents formation under the acceptance rule. Courts examine whether the offeree used words such as "limited to" or "conditional on" the new terms. Vague requests for changes do not meet the threshold.
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The response does not operate as an acceptance, so no contract forms on the offer plus additional terms. The parties may still create a contract through their subsequent conduct recognizing the existence of an agreement. Only terms on which the writings agree plus gap fillers enter that contract.
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Silence alone does not supply the required assent to the additional or different terms. The offeror must take affirmative action showing agreement to the condition before the response can function as an acceptance. Conduct recognizing a contract may still bind the parties under the conduct rule instead.
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The condition blocks the response from becoming an acceptance in the first place, so the merchant rule for adding nonmaterial terms never applies. The analysis shifts to whether the parties' later conduct formed a contract and what terms that conduct incorporates.
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…as an acceptance even though it states terms additional to or different from those offered or agreed upon, unless acceptance is expressly made conditional on assent to the additional or different terms. (2) The additional terms are to be construed as proposals for addition to the contract. Between merchants such terms become part of the contract…